Sieving characteristics of cytokine- and peroxide-induced epithelial barrier leak: Inhibition by berberine

Table 1 The effect of tumor necrosis factor-α + interferon-γ + interleukin-1β and hydrogen peroxide on transepithelial flux of ¹⁴C-polyethylene glycol and ¹²⁵I-epidermal growth factor

	14C-PEG flux		125I-EGF flux
	cpm/min per square centimeter	pmol/min per square centimeter	cpm/min per square centimeter	fmol/min per square centimeter
Control	3.74 ± 0.07	7.54 ± 0.20	43.7 ± 2.0	0.034 ± 0.005
Cytomix	3.40 ± 0.12	6.87 ± 0.27	30.3 ± 1.4	0.015 ± 0.001
Cytomix/H2O2	9.80 ± 0.28a	20.97 ± 0.64a	192.0 ± 4.0c	1.21 ± 0.029c

^aP < 0.05 vs control;

^cP < 0.05 vs Cytomix-only condition (one-way ANOVA followed by Tukey’s post hoc testing). CACO-2 cell layers on Millipore polycarbonate filters were refed in control medium or medium containing the combination of 50 ng/mL tumor necrosis factor-α, 100 ng/mL interferon-γ, and 50 ng/mL interleukin-1β (apical and basal-lateral compartments) for 48 h. On the day of radiotracer flux studies, the cell layers were exposed to control saline or saline containing 1 mmol/L hydrogen peroxide for 3 h. These studies were performed using 0.1 mmol/L, 0.025 μCi/mL

¹⁴C-polyethylene glycol (MW 4000) and 10 nmol/L, 0.5 μCi/mL

¹²⁵I-EGF (MW 6100), as described in Materials and Methods. Total ¹²⁵I flux rates (as cpm/min per square centimeter) were adjusted, based upon the percent of intact ¹²⁵I-EGF in the basal-lateral compartment (using column chromatography), and expressed finally as fmol/min per square centimeter. Similar gel chromatography analyses were performed for ¹⁴C-PEG experiments, but here all isotopes that diffused across the epithelial cell layer was found to be 4000 MW PEG. Data shown represent the mean standard error for an n = 8 in all cases. PEG: Polyethylene glycol; EGF: Epidermal growth factor.